Tunnelling machines and the like

ABSTRACT

A tunneling machine is provided with one or more cutter heads with rotary cutters driven by a motor in each cutter head and swingably mounted in a front frame portion of the machine on an axis directed transversely to the longitudinal direction of the machine or tunnel. The front frame portion has supporting wall engaging shoes capable of being pressed against the tunnel walls for holding the front frame portion in fixed position and to loosen the grip in the walls when the front frame portion is fed forward or swung in any direction for steering purposes. The swinging axes of the cutter heads are offset from the axes along which the shoes press against the walls to facilitate service and supervision of the cutter heads.

United States Patent Lauber et al.

[ Mar. 7,1972

Inventors:

Ernst Abraham Lauber; Lorne Robert Herron, both of Thun, Switzerland Atlas Copeo Aktiebolag, Nacka, Sweden Mar. 19, 1970 US. Cl ..299/3l, 299/18, 299/71,

299/86 Int. Cl ..E2lc 29/02, E01 g 3/04 Field ofSearch ..299/3l,7l

[56] References Cited UNITED STATES PATENTS J 9 l f 30 I an. 27 Q.

FOREIGN PATENTS OR APPLICATIONS 997,519 7/1965 Great Britain ..299/31 Primary Examiner-Ernest R. Purser Attorney-Munson & Fiddler [57] ABSTRACT A tunneling machine is provided with one or more cutter heads with rotary cutters driven by a motor in each cutter head and swingably mounted in a front frame portion of the machine on an axis directed transversely to the longitudinal direction of the machine or tunnel. The front frame portion has supporting wall engaging shoes capable of being pressed against the tunnel walls for holding the front frame portion in fixed position and to loosen the grip in the walls when the front frame portion is fed forward or swung in any direction for steering purposes. The swinging axes of the cutter heads are offset from the axes along which the shoes press against the walls to facilitate service and supervision of the cutter heads.

11 Claims, 11 Drawing Figures 5 I: m 29 I mgi aii l/ PATENTEDHAR 71972 sum 1 or 6 ERNST ABRAHAM LAUBER and LORNE ROBERT HERRON INVEN'I'ORS BY 7 MUNSON & FIDDLBR,

Attorneys.

PATENIEDHAR were 3,647, 263 SHEET 2 or 6 I vw S E ow Q 8 mm HI #1 .m M Gm V W 0m GN W R@ m M ERNST ABRAHAM LAUBER and LORNE ROBERT HERRON IN VENTORs BY MUNSON & FIDDLER,

Attorneys.

PATENTEDMAR H972 3,647,263

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BY MUNSON & FIDDLBR,

Attorneys.

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Attorneys.

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, Attorneys TUNNELLING MACHINES AND THE LIKE This invention relates to tunneling machines and the like having one or more cutter heads swingable on one or more axes extending transversely to the longitudinal direction of the machine and a tunnel. One object of the invention is to provide a tunneling machine having one or more cutter heads swingable transversely to the longitudinal axis of the machine and movable to positions facilitating service and supervision on the cutter heads. Another object of the invention is to enable the cutter heads to be swung to positions which permit steering of the tunneling machine in curves with a radius which is small as compared with the length of the machine. A still further object of the invention is to provide a tunneling machine of the type described in which the machine frame can be held fixed in a tunnel during a swing cut action of a cutter head and during supervision and repair work on the cutter head or heads to avoid accidents. A still further object of the invention is to provide a tunneling machine of the type described in which the cutter head or cutter heads are easily accessible for the tunneling machine personnel during operation for supervision of the operation. The cutter head of heads may be of various designs according to the purpose of the work to be done and the properties of the tunnel wall material, such as hardness, cuttability, etcetera. Further objects of the invention will become apparent from the following description of some embodiments of tunneling machines according to the invention, which are examples only of the invention, the scope of which is only limited by the claims. Tunneling machines according to the invention may be used for producing sewage tunnels, road tunnels, fresh water tunnels, drifts in mines, shafts in mines and water power stations, as continuous miners, and for other purposes.

On' the drawings FIG. 1 is a perspective view of a tunneling machine according to the invention provided with four cutter heads.

FIG. 2 is a front end view of the machine in FIG. 1 looking from the tunnel face, and

FIG. 3 is a plan view of the tunneling machine according to FIG. 1.

FIGS. 4-9 are diagrammatic views of tunneling machines according to the invention in various modified arrangements.

FIG. is a plan view and partial section and FIG. 11 is a side view and partial section of a machine with two groups of cutter heads with three cutter heads in each group.

The tunneling machine according to F lGS. 1-3 has a frame structure which consists of a front frame portion 1 and a rear frame portion 2 which are pivotally interconnected by means of two pairs of double-acting hydraulic cylinders 3-6 and piston rods 7-10, respectively. The front frame portion 1 has a lower deck 11 and an upper deck 12 which are rigidly interconnected by three vertical columns 13, I4, 14 so as to form a very stiff and rigid frame structure. The columns 14, 14 are designed as hydraulic jacks or rams and are provided with wall engaging means, such as shoes 15, 16, 17 carried on the ends of piston rods 18, 19, 20. The left-hand column 14 is not illustrated in FIG. 1, since it is substantially concealed by other parts of the machine. Two pairs of cutter heads 21, 22 and 23, 24, respectively, comprising motor-driven rotary cutters 39 carried by motor and transmission casings 25, 26 are mounted to swing on parallel axes extending transversely to the longitudinal direction of the tunnel and of the machine. The motor and transmission casings of each pair are for this purpose built together with a segment member 40 mounted on pivots journaled in bearings indicated at 27 and 28 for the rightand lefthand pair of cutter heads. The cutter heads may be of any conventional type according to the properties and cuttability of the material in which the tunneling machine is intended to operate. In the illustrated embodiment in FIGS. l-3 the cutter heads are of a type having disk-shaped cutters 39 with teeth which cut a kerf in the material of the tunnel wall. The cutterheads have additional material removing or reaming members 29 which may serve to break away rock portions left by the cutter teeth 39 and/or to smoothen the tunnel wall or roof and floor. The front frame portion I is provided with a pair of wall engaging members or shoes 30 of large size, the lower one being concealed under the lower deck 11. The upper wall engaging shoe 30 is carried and universally pivotable on a piston rod 31 forming a portion of a ram similar to the rams 14. The shoes 15, 16, 17, 30 are designed for engaging the roof and floor of the tunnel and the tunneling machine is provided with further shoes 32 provided on piston rods 33 of hydraulic cylinders 34 on each side of the front frame portion 1 serving to steady the machine or to engage the sidewalls of the tunnel in order to help to hold the front frame portion in fixed position in the tunnel or to guide it during the walking action when they may be locked in nongripping position in which their oil pressure may be reduced to a lower pressure level than the pressure necessary for gripping the walls. A double-acting hydraulic cylinder 35 and piston rod 36 is arranged in the front frame portion 1 and pivotally connected to the from frame portion and at 37 to a lug on the segment member 40 of the right-hand pair of cutter heads. The machine is fed forward during the initial cutting operation shown in FIG. 3 and some shoes on the from frame portion may then be locked whereas other shoes opposed to said locked shoes are engaging the walls at reduced pressure. The swinging piston rod 36 is then completely retracted as obvious from FIG. 3. When the advancing cut in the sidewalls has been completed as in FIG. 3 the gripping shoes 16, 17, 30 and 32 are pressed into gripping engagement with the tunnel walls and swinging of the cutter heads with the cylinders 35 and piston rod 36 takes place. This mode 'of operation results in a more even tunnel sidewall. The double-acting hydraulic cylinder 35 and piston rod 36 swings the pair of cutter heads 21, 22 through an angle which is in excess of so much that the cutter heads get an effective start in cutting into the sidewall of the tunnel and produce an overlap of the longitudinal center line of the tunnel thereby producing a tunnel profile with a substantially flat floor and roof and slightly curved sidewalls, each cutter producing a cavity which has substantially the shape of a sector of a big cheese with flat top and bottom. The upward and downward incline of the cutter axes provides better space around the cutter heads and for the roof and floor engaging shoes.

The rear frame portion 2 of the tunneling machine shown in FlGS. 1-3 consists of an upper deck 41 and a lower deck 42 which are connected by columns 43 and 44 which at their bottom and top ends carry wall engaging shoes 45, 46, 47, 48, respectively. The shoes 46, 48 are fitted on piston rods movable in the columns 43, 44 so as to form jacks for holding the rear frame portion 2 in fixed position in a tunnel when the wall engaging shoes 45-48 are pressed against the floor and roof of the tunnel. The shoes 45, 47 are universally pivoted to the columns 43, 44, respectively. The rear frame portion 2 is provided with wall engaging members or shoes 53, 54 for engaging the sidewalls of the tunnel and fitted on piston rods 55, 56 of hydraulic cylinders 57, 58. The arrangement of the shoes 53, 54 is similar to the arrangement of the shoes 32 in the front frame portion. These shoes 53, 54, 32 are also connected to their respective frame portions by link members 59 pivoted to brackets 38 on the columns 14, 43, 44 and to the shoes 32, 53, 54.

The frame portion 1 has a rearwardly extending beam 64 which carries a drivers compartment 49 with an operator's seat 50 and a maneuvering panel 51 with control levers 52 for controlling the operation of the cutter heads and the various hydraulic cylinders and other machinery in the tunneling machine.

The material of the tunnel walls removed by the cutters 39 and members 29 is transported towards the center portion of the front frame portion by the action of the cutters 39 and members 29 which operate as gathering members for the debris. For this purpose the cutters rotate as indicated by the arrows and the cutter heads swing towards the center line of the machine on the working strokes. The debris is collected in the center portion of the machine and transported towards the rear end of the machine by means of a scraper conveyor 60 which extends around the lower decks of the machine and is driven by a motor 61. The conveyor is attached to the front frame portion 1. 62 is a direction indicator board which helps the operator to steer the machine in such a manner that a desired tunnel direction is obtained. For this purpose a laser is provided on the tunnel wall behind the machine and produces an illuminated point on the indicator board 62.

In operation the machine starts cutting substantially with the cutter heads in the position illustrated in FIG. 3. The cutter heads are in the swing back position of FIG. 3 and the cutters rotate. The shoes of the front frame portion are under nongripping oil pressure and the frame portion 1 is advanced a distance 65 corresponding to the feed. This is the position reached in FIG. 3. The gripping shoes of the front frame portion are then pressed to grip the walls and fix the frame portion in the tunnel. The swinging of the cutter heads by 35, 36 is initiated and the teeth of the cutters cut a kerf in the tunnel wall material and the remaining wall portions left at the back of the cutter teeth are broken away by the conical surfaces 66 and by the members 29 or otherwise. This mode of operation is very well known for instance from the Wohlmeyer US. Pat. No. 2,758,825 and the swinging cutter head action is also well known from the Lauber US. Pat. No. 3,446,535 and others. When the two pairs of cutters have fulfilled their swinging and cutting action from the side position towards the center position they return idle back to the side and back swung position. The. gripping shoes of the front frame portion are brought into nongripping or sliding position and a new feed cut is started. The feeding motion is produced by the hydraulic cylinders 3, 4, 5, 6 while the shoes 15, 16, 17, 30 and 32 are under nongripping pressure. The above-described steps are then repeated. Naturally, the left-hand and right-hand cutters must be synchronized so as not to interfere with each other near the center line of the machine, and for this purpose the swinging of one pair is delayed slightly when the cutter approaches the center line with respect to the other pair in their swinging action.

When the front frame portion 1 has been advanced so many cutting or feeding steps 65 as corresponds substantially to the stroke of the hydraulic cylinders 3, 4, 5, 6 then the front frame portion 1 is fixed in the tunnel and the rear frame portion is released from the tunnel walls and the hydraulic cylinders 3-6 are contracted so that the rear frame portion 2 of the tunneling machine is advanced towards the front frame portion 1 as much as corresponds to the available stroke of the hydraulic cylinders 3-6, whereupon the rear frame portion is fixed in the tunnel. Operation is thereafter continued in the manner described hereinbefore.

If it is desired to steer the tunneling machine for instance to the left the gripping shoes of the front frame portion are brought into nongripping or sliding position, whereas the gripping shoes of the rear frame portion are kept in gripping position. The machine is then operated as above described for making a feed cut, but the cylinders 3, 6 are expanded less than the cylinders 4, during the feed cut. The swing and cut operation as above described is then carried out, and after swinging back the cutter heads a new feed cut is made as just described. The above operations may be repeated until the desired turn of the machine has been achieved. For making a right turn the feed cut of the right-hand cutters is reduced. For dumping the feed cut of the bottom cutters are reduced and for raising the feed cut of the roof cutters are reduced.

Steering of the machine may also be accomplished by bringing one the shoes l6, 17 or 30 in gripping position, producing a reduced feed cut or a negative feed with one pair of cutters and a full feed cut with the other pair and thereafter making a swinging cut with both pairs. This procedure may be repeated as many times as the geometrical form of the machine permits. The arrangement of the machine provides a great variety of possibilities for steering of the machine in various directions by manipulating the cylinders 3-6 and the gripping shoes in various ways.

Changing the direction to a more downward direction may, for instance, be produced by disengaging the gripping shoes of the front frame portion 1, locking the hydraulic cylinders 5, 6 and expanding the cylinders 3, 4 and simultaneously making a feed cut. The front frame portion is then fixed and a swinging cut is made and the steps are repeated as many times as desired. Similarly, the machine may be made to rise by locking the cylinders 3, 4 and expanding the cylinders 5, 6 and simultaneously making a feed cut etcetera.

The debris produced by the tunneling machine is gathered centrally on the conveyor 60 by the cutter heads and cutters and scraped by the conveyor 60 to the discharge chute 63 which leads to a conveyor or transportation means (not illustrated) for transporting the debris towards the tunnel opening.

It would be obvious to anyone that the above-described machine contains a considerable number of components which are identical such as the four cutter heads, the four hydraulic cylinders 3-6, the wall engaging shoes 30, 46, 48 etcetera and, consequently, the machine is fairly cheap in construction and also the maintenance and the store of spare parts may be kept low.

In the diagrammatic FIGS. 4-9 the cutter heads are designated with the same numeral as the cutter head 21 in FIGS. 1-3, the equivalent frame portions are similarly designated 1 and 2 for the front and rear frame portions, respectively, the sidewall engaging shoes are all designated 32 on the front frame portion and 53 on the rear frame portion, since they fill the same functions as the corresponding shoes in FIGS. 1-3. The roof and floor engaging shoes are similarly designated 30 when on the front frame portion and 46 when on the rear frame portion, and the chute for delivering debris to the out-transportation means is designated 63 as in FIG. 1. The various embodiments in FIGS. 4-9 differ with respect to the number and geometrical arrangement of the various components. FIG. 4, for instance, illustrates a machine which has a single cutter head and one pair of floor and roof engaging shoes 30 on the front frame portion 1 and another pair of floor and roof engaging shoes 46 on the rear frame portion 2, respectively. In FIG. 6 two cutter heads 21 are arranged side by side thus providing a wider tunnel opening the arrangement being similar to FIGS. 1-3. FIG. 7 illustrates an arrangement with two pairs of roof and floor engaging shoes in the front frame portion 1 and two pairs of floor and roof engaging shoes 46 in the rear frame portion. The conveyor 63 is located centrally which is an advantage of this embodiment. FIG. 8 illustrates a similar arrangement as FIG. 7 with one pair of roof and floor engaging shoes 30 in the front frame portion. This arrangement provides greater movability for the cutter heads 21 in that they may be swung further backwards, if desired for service and other supervision. FIG. 9 illustrates an arrangement with three sets of cutter heads 21 provided side by side in the front frame portion 1. In vertical direction the number of cutter heads in the various embodiments may be one, two or more according to the desired height of the tunnel. FIG. 5 illustrates diagrammatically a forward frame portion with two cutter heads provided one above the other on a common swinging segment member which is the arrangement used in FIG. 1. All the above embodiments have in common that the cutter heads are swingable on axis which do not extend along the same axis as the common axis for the top and bottom floor engaging members of each ram or jack in each pair.

In the tunneling machine illustrated in FIGS. 10 and 11 the elements equivalent to similar elements in FIGS. 1-3 are designated with the same reference numerals as in FIGS. I-3 and are not described again. FIGS. 10 and 11 show the front and rear frame portions 1 and 2, respectively, of the machine and also a part of a trailer 70 which carries hydraulic pumps and motors for driving the pumps, ventilation units with a suction hose 71, conveyors 72, 73 and other accessories. The trailer 70 is connected to the rear frame portion 2 by a draw bar 74. The front frame portion 1 has two groups of cutter heads 75 with three cutter heads in each group mounted on segment members 40 for lateral swinging by means of pairs of double-acting cylinder and piston and piston rod element 35, 36. The cutter heads and cutters 39 are generally of the same construction as the cutter heads 21-24 and comprise motors 67, transmission casings 68 and rotary cutters with kerf cutting teeth. The front end of the portion 1 rests on the tunnel floor with two wide shoes 76, 77 and a conveyor 78 is centrally located in the front frame portion 1 near the tunnel floor. The lower cutter heads and cutters move the debris on to the loading end of said conveyor. The conveyor is enclosed in a duct 79 which communicates with the suction hose 71 for removing dust from the front of the machine. The conveyor 78 discharges in a transverse conveyor 72 to permit the machine to operate in curves.

The front frame portion 1 has two oppositely directed shoes 80, 81 at least one of which is operable in gripping engagement with the sidewall of the tunnel by a powerful hydraulic jack or ram 82 which forms the main means for fixing the front frame portion 1 in the tunnel during the swinging cut of the cutter heads. The rear frame portion 2 has similar pairs of shoes at least the shoes 83 being operable into wall gripping position by hydraulic jacks or rams 85, 86 are trimming cylinders or jacks. A dust shield extends transversely of the machine substantially along a transverse plane at 87. The arrangement makes possible to fix the frame portions in the tunnel by pressing wall engaging shoes against the tunnel sidewalls only without producing a thrust against the ceiling which is often undesireable.

The walking action of the machine in the tunnel and the feed cuts as well as the swinging cuts are performed in the same manner as with the machine of FIGS. 1-3, and the steering may also be carried out in similar way and would therefor not have to be described again.

Naturally the invention may be modified in several different ways within the scope of the following claims and the embodiments above described should only be considered as examples.

What we claim is:

1. In a tunneling machine, a frame structure having a front portion and a rear portion, a number of tunnel wall engaging shoes on said front portion engageable with walls of a tunnel for guiding the front portion in the tunnel, a number of tunnel wall engaging shoes on said rear portion engageable with said tunnel walls for gripping the walls, at least one power jack operable on a first axis transverse of the tunnel wall to move one of said shoes of the front frame portion to grip the wall for fixing the front frame portion in the tunnel, at least one power jack operable to move one of said shoes of the rear frame portion to grip the wall for fixing the rear frame portion in the tunnel, double-acting power means for moving one of the frame portions in nongripping position while sliding the shoes under pressure against the tunnel wall longitudinally of the tunnel relative to the other said portion for producing a walk ing action of the machine in the tunnel, and a cutter head assembly having at least two cutter heads with built in motor and motor driven rotary cutter mounted to swing on the front frame portion on a second axis transverse to the tunnel axis parallel to and offset from said first transverse axis a distance sufficient to make said cutter heads accessible for service.

2. A tunneling machine according to claim 1, having at least two cutter head assemblies each comprising at least two cutter heads, which cutter heads are mounted to swing on the front frame portion on two parallel axes transverse to the tunnel axis.

3. A tunneling machine according to claim 2, in which each cutter assembly comprises a segment carrying the cutter heads, said segment being in turn mounted to swing on the front frame portion on said second axis.

4. A tunneling machine according to claim 2, in which two cutter head assemblies with three cutter heads in each assembly are mounted individually on a segment member, said two segment members being in turn mounted to swing on the front frame portion on two parallel axes transverse to the tunnel axis which axes are offset from said first transyerseaxis.

5. A tunneling machine according to claim 1, in which each rotary cutter comprises a cutter disk provided with peripherally disposed kerf cutting teeth movable so as to undercut the tunnel wall material.

6. A tunneling machine according to claim 5, in which each rotary cutter comprises a cutter disk provided with peripherally disposed kerf producing elements and a number of reaming elements arranged axially behind said kerf producing elements.

7. In a tunneling machine, a frame structure having a front portion and a rear portion, a number of tunnel wall engaging shoes on said front portion engageable with walls of a tunnel for guiding the front portion in the tunnel, a number of tunnel wall engaging shoes on said rear portion engageable with said tunnel walls for gripping the walls, at least one power jack operable to move one said shoes of a pair of oppositely directed shoes of the front frame portion acting on a transverse axis of the tunnel to grip the wall for fixing the front frame portion in the tunnel, at least one power jack operable to move one of said shoes of the rear frame portion to grip the wall for fixing the rear frame portion in the tunnel, double-acting power means for moving one of the frame portions in nongripping position of its shoes while sliding the shoes under pressure against the tunnel wall longitudinally of the tunnel relative to the other said portion for producing a walking action of the machine in the tunnel, at least two cutter heads with built in motor and motor driven rotary cutters mounted to swing on the front frame portion on two parallel swinging axes transverse to the tunnel axis and offset from said transverse axis of said pair of oppositely directed shoes of the front frame portion, and double-acting power cylinder and piston and piston rod means in the front frame portion for swing each cutter head through an angle of more than to produce a cut in the tunnel front.

8. A tunneling machine according to claim 7, in which the rotary cutter comprises a cutter disk provided with a number of peripherally disposed kerf cutting teeth.

9. A tunneling machine according to claim 7, in which the rotary cutter comprises a cutter disk provided with a number of peripherally disposed kerf producing elements and a number of reaming elements arranged axially behind said kerf producing elements.

10. A tunneling machine, according to claim 7 in which at least two cutter heads with built in motor and motor-driven rotary cutters are mounted to swing on the front frame portion on two parallel substantially vertical swinging axes transverse to the tunnel axis, the direction of rotation of said cutters situated adjacent the tunnel floor being such as to help to move debris towards the center line of the tunnel, and power means in the front frame portion for swinging said cutter heads towards said center line through an angle of more than 90 to produce a cut in the tunnel front.

11. A tunneling machine according to claim 10, in which a conveyor for debris is provided with a receiving end near the tunnel floor at a front end of the front portion substantially in the midportion of said front end between the two parallel swinging axes. 

1. In a tunneling machine, a frame structure having a front portion and a rear portion, a number of tunnel wall engaging shoes on said front portion engageable with walls of a tunnel for guiding the front portion in the tunnel, a number of tunnel wall engaging shoes on said rear portion engageable with said tunnel walls for gripping the walls, at least one power jack operable on a first axis transverse of the tunnel wall to move one of said shoes of the front frame portion to grip the wall for fixing the front frame portion in the tunnel, at least one power jack operable to move one of said shoes of the rear frame portion to grip the wall for fixing the rear frame portion in the tunnel, double-acting power means for moving one of the frame portions in nongripping position while sliding the shoes under pressure against the tunnel wall longitudinally of the tunnel relative to the other said portion for producing a walking action of the machine in the tunnel, and a cutter head assembly having at least two cutter heads with built in motor and motor driven rotary cutter mounted to swing on the front frame portion on a second axis transverse to the tunnel axis parallel to and offset from said first transverse axis a distance sufficient to make said cutter heads accessible for service.
 2. A tunneling machine according to claim 1, having at least two cutter head assemblies each comprising at least two cutter heads, which cutter heads are mounted to swing on the front frame portion on two parallel axes transverse to the tunnel axis.
 3. A tunneling machine according to claim 2, in which each cutter assembly comprises a segment carrying the cutter heads, said segment being in turn mounted to swing on the front frame portion on said second axis.
 4. A tunneling machine according to claim 2, in which two cutter head assemblies with three cutter heads in each assembly are mounted individually on a segment member, said two segment members being in turn mounted to swing on the front frame portion on two parallel axes transverse to the tunnel axis which axes are offset from said first transverse axis.
 5. A tunneling machine according to claim 1, in which each rotary cutter comprises a cutter disk provided with peripherally disposed kerf cutting teeth movable so as to undercut the tunnel wall material.
 6. A tunneling machine according to claim 5, in which each rotary cutter comprises a cutter disk provided with peripherally disposed kerf producing elements and a number of reaming elements arranged axially behind said kerf producing elements.
 7. In a tunneling machine, a frame structure having a front portion and a rear portion, a number of tunnel wall engaging shoes on said front portion engageable with walls of a tunnel for guiding the front portion in the tunnel, a number of tunnel wall engaging shoes on said rear portion engageable with said tunnel walls for gripping the walls, at least one power jack operable to move one said shoes of a pair of oppositely directed shoes of the front frame portion acting on a transverse axis of the tunnel to grip the wall for fixing the front frame portion in the tunnel, at least one power jack operable to move one of said shoes of the rear frame portion to grip the wall for fixing the rear frame portion in the tunnel, double-acting power means for moving one of the frame portions in nongripping position of its shoes while sliding the shoes under pressure agaiNst the tunnel wall longitudinally of the tunnel relative to the other said portion for producing a walking action of the machine in the tunnel, at least two cutter heads with built in motor and motor driven rotary cutters mounted to swing on the front frame portion on two parallel swinging axes transverse to the tunnel axis and offset from said transverse axis of said pair of oppositely directed shoes of the front frame portion, and double-acting power cylinder and piston and piston rod means in the front frame portion for swing each cutter head through an angle of more than 90* to produce a cut in the tunnel front.
 8. A tunneling machine according to claim 7, in which the rotary cutter comprises a cutter disk provided with a number of peripherally disposed kerf cutting teeth.
 9. A tunneling machine according to claim 7, in which the rotary cutter comprises a cutter disk provided with a number of peripherally disposed kerf producing elements and a number of reaming elements arranged axially behind said kerf producing elements.
 10. A tunneling machine, according to claim 7 in which at least two cutter heads with built in motor and motor-driven rotary cutters are mounted to swing on the front frame portion on two parallel substantially vertical swinging axes transverse to the tunnel axis, the direction of rotation of said cutters situated adjacent the tunnel floor being such as to help to move debris towards the center line of the tunnel, and power means in the front frame portion for swinging said cutter heads towards said center line through an angle of more than 90* to produce a cut in the tunnel front.
 11. A tunneling machine according to claim 10, in which a conveyor for debris is provided with a receiving end near the tunnel floor at a front end of the front portion substantially in the midportion of said front end between the two parallel swinging axes. 